The heparins: all a nephrologist should know

Anticoagulation in Chronic Kidney Disease

The nuanced landscape of anticoagulation therapy in patients with chronic kidney disease (CKD) presents a formidable challenge, intricately balancing the dual hazards of hemorrhage and thrombosis. These patients find themselves in a precarious position, teetering on the edge of these risks due to compromised platelet functionality and systemic disturbances within their coagulation frameworks. The management of such patients necessitates a meticulous approach to dosing adjustments and vigilant monitoring to navigate the perilous waters of anticoagulant therapy. This is especially critical considering the altered pharmacokinetics in CKD, where the clearance of drugs is significantly impeded, heightening the risk of accumulation and adverse effects. In the evolving narrative of anticoagulation therapy, the introduction of direct oral anticoagulants (DOACs) has heralded a new era, offering a glimmer of hope for those navigating the complexities of CKD. These agents, with their promise of easier management and a reduced need for monitoring, have begun to reshape the contours of care, particularly for patients not yet on dialysis. However, this is not without its caveats. The application of DOACs in the context of advanced CKD remains a largely uncharted territory, necessitating a cautious exploration to unearth their true potential and limitations. Moreover, the advent of innovative strategies such as left atrial appendage occlusion (LAAO) underscores the dynamic nature of anticoagulation therapy, potentially offering a tailored solution for those at the intersection of CKD and elevated stroke risk. Yet the journey toward integrating such advancements into standard practice is laden with unanswered questions, demanding rigorous investigation to illuminate their efficacy and safety across the spectrum of kidney disease. In summary, the management of anticoagulation in CKD is a delicate dance, requiring a harmonious blend of precision, caution, and innovation. As we venture further into this complex domain, we must build upon our current understanding, embracing both emerging therapies and the need for ongoing research. Only then can we hope to offer our patients a path that navigates the narrow strait between bleeding and clotting, toward safer and more effective care.

Smaller nadroparin dose reductions required for patients with renal impairment: A multicenter cohort study

BACKGROUND

Guidelines advise 50 % and 25 % dose reduction of the therapeutic nadroparin dose (86 IU/kg) in patients with eGFR 15-29 and 30-60 ml/min respectively. For monitoring, peak anti-Xa levels are suggested. Data lack whether this results in therapeutic anti-Xa levels or in anti-Xa levels that are comparable to those of patients without renal impairment.

AIMS

To determine dose ranges in patients with renal impairment that result in therapeutic anti-Xa levels and to determine the percentage of the 86 IU/kg dose that results in anti-Xa levels normally occurring in patients without renal impairment.

METHODS

A retrospective cohort study was conducted in five hospitals. Patients ≥18 years of age, with an eGFR ≥ 15 ml/min were included. The first correctly sampled peak (i.e. 3-5 h after ≥ third administration, regardless of dose per patient) was included. Simulated prediction models were developed using multiple linear regression.

RESULTS

770 patients were included. eGFR and hospital affected the association between dose and anti-Xa level. The doses for peak anti-Xa levels of 0.75 IU/ml differed substantially between hospitals and ranged from 55 to 91, 65-359 and 68-168 IU/kg in eGFR 15-29, 30-60 and > 60 ml/min/1.73m2, respectively. In eGFR 15-29 and 30-60 ml/min/1.73m2, doses of 75 % and 91 % of 86 IU/kg respectively, were needed for anti-Xa levels normally occurring in patients with eGFR > 60 ml/min.

CONCLUSION

We advise against anti-Xa based dose-adjustments as long as anti-Xa assays between laboratories are not harmonized and an anti-Xa target range is not validated. A better approach might be to target levels similar to eGFR > 60 ml/min/1.73m2, which are achieved by smaller dose reductions.

End-on PEGylation of heparin: Effect on anticoagulant activity and complexation with protamine

Heparin is the most common anticoagulant used in clinical practice but shows some downsides such as short half-life (for the high molecular weight heparin) and secondary effects. On the other hand, its low molecular weight analogue cannot be neutralized with protamine, and therefore cannot be used in some treatments. To address these issues, we conjugated polyethylene glycol (PEG) to heparin reducing end (end-on) via oxime ligation and studied the interactions of the conjugate (Hep-b-PEG) with antithrombin III (AT) and protamine. Isothermal titration calorimetry showed that Hep-b-PEG maintains the affinity to AT. Dynamic light scattering demonstrated that the Hep-b-PEG formed colloidal stable nanocomplexes with protamine instead of large multi-molecular aggregates, associated with heparin side effects. The in vitro (human plasma) and in vivo experiments (Sprague Dawley rats) evidenced an extended half-life and higher anticoagulant activity of the conjugate when compared to unmodified heparin.

Therapeutically dosed low molecular weight heparins in renal impairment: a nationwide survey

PURPOSE

International guidelines vary in their recommendations whether or not to reduce the therapeutic dose of low molecular weight heparins (LMWHs) in renal impairment. The use of anti-Xa monitoring as a basis of dose adjustments is also a matter of debate. As this may lead to variations in treatment policies, we aimed to study the treatment policies of therapeutically dosed LMWHs in renal impairment in Dutch hospitals.

METHODS

An 11-item survey was distributed between June 2020 and March 2021 to hospital pharmacists, representing Dutch hospital organisations. Primary outcomes were the dosing regimens of therapeutically dosed LMWHs in renally impaired patients. Secondary outcomes were the proportion of hospitals that used anti-Xa monitoring and the anti-Xa target range used.

RESULTS

There was a response from 56 of 69 (81%) Dutch hospital organisations where in each case a hospital pharmacist completed the survey. In these hospitals, 77 LMWH regimens were in use. In 76 of 77 (99%) regimens, a regular dose reduction was used at the start of treatment. Fifty-five of these hospitals used a dose reduction if estimated glomerular filtration rate (eGFR) < 50 ml/min and 17 used a dose reduction if eGFR < 30 ml/min. Anti-Xa levels were not routinely monitored in 40% of regimens, while 22% monitored anti-Xa if eGFR < 50 ml/min, 27% if eGFR < 30 ml/min and 10% in other eGFR cutoff values. Target ranges of 1.0-2.0 IU/ml (once daily) and 0.5/0.6-1.0 IU/ml (twice daily) were used in 69% of regimens that included monitoring of anti-Xa.

CONCLUSION

Treatment policies show substantial diversity in therapeutically dosed LMWHs in renally impaired patients. The most commonly used treatment regimen was a regular dose reduction if eGFR is < 50 ml/min, without anti-Xa monitoring.

Venous Thromboembolism In Cancer Patients: "From Evidence to Care"

This article seeks to review the current status of treatment and prevention of venous thromboembolic disease (VTE) in cancer patients after the addition of direct oral anticoagulants (DOAC) to the therapeutic arsenal available. The suitability of DOAC use in complex clinical situations, poorly represented in clinical trials, is controversial and difficult for care activity, making the recommendations in clinical practice guidelines the focus of special attention in this area. Recently, several randomized trials have compared low molecular weight heparin (LMWH) to DOAC for the management of CAT. Potential drug interactions with DOACs or the increased risk of bleeding in intraluminal tumors require special precautions, as do metastatic or primary brain disease and comorbid conditions, such as renal or liver failure, which are not suitably represented in pivotal studies. Furthermore, few data are available for situations involving elevated bleeding risk, with thrombocytopenia levels below the inclusion criterion of clinical trials, or recurrence during active anticoagulant therapy. Similarly, it is less clear that patients and physicians accept the presumption that oral DOAC administration is more convenient than subcutaneous LMWH, particularly when drug absorption may be compromised. The non-inclusion or under-representation of patients at higher risk for complications with anticoagulation in randomized clinical trials, makes their use complex in certain situations in health care. This paper provides a practical review of current clinical guideline recommendations regarding LMWH and/ or DOAC to treat and prevent CAT, as well as the most controversial clinical conditions for their use.

The Impact of Anticoagulation on COVID-19 (SARS CoV-2) Patient Outcomes: A Systematic Review

BACKGROUND

Emerging data suggest that coagulopathy, cytokine storm, and acute respiratory distress syndrome are associated with the 2019 coronavirus disease (COVID-19). The prevalence of hypercoagulable state in these patients is unknown, but appears to be higher compared to those with other critically ill patients. Elevated D-dimer, large blood vessels clots, deep vein thrombosis, pulmonary embolism and disseminated intravascular coagulation have been reported in patients diagnosed with COVID-19 either on admission or during hospitalization and may be predictors of poor outcomes.

METHODS

We performed a comprehensive literature review using the search terms of COVID-19; severe acute respiratory syndrome coronavirus-2, coagulopathy, thrombosis and anticoagulation in PubMed, Ovid, google scholar, Medline and EMBASE databases from December 2019 to May 30, 2020.

RESULTS

A total of 64 relevant studies were reviewed; of which, 4 studies met the inclusion criteria and were included for analysis. The majority of the studies were retrospective involving 525 critically ill COVID-19 patients. The most commonly studied anticoagulant administered was low molecular weight heparins. Anticoagulation dosing varied throughout the studies and may be classified as standard venous thromboembolism prophylaxis, intermediate dosing, or full dose anticoagulation. The most studied objective was improvement in coagulopathy. Significant reduction in D-dimer, improvement in coagulopathy markers such as Interlukin-6, fibrinogen degradation product level, as well as lymphocyte count were reported.

CONCLUSION

Despite the limited quality of studies analyzed, prophylaxis and higher intensity dosed anticoagulation is associated with improved pulmonary oxygenation, decreased coagulopathy markers and decreased mortality in COVID-19 patients.

Silver-assisted gold-catalyzed formal synthesis of the anticoagulant Fondaparinux pentasaccharide

Clinically approved anti-coagulant Fondaparinux is safe since it has zero contamination problems often associated with animal based heparins. Fondaparinux is a synthetic pentasaccharide based on the antithrombin-binding domain of Heparin sulfate and contains glucosamine, glucuronic acid and iduronic acid in its sequence. Here, we show the formal synthesis of Fondaparinux pentasaccharide by performing all glycosidations in a catalytic fashion for the first time to the best of our knowledge. Designer monosaccharides were synthesized avoiding harsh reaction conditions or reagents. Further, those were subjected to reciprocal donor-acceptor selectivity studies to guide [Au]/[Ag]-catalytic glycosidations for assembling the pentasaccharide in a highly convergent [3 + 2] or [3 + 1 + 1] manner. Catalytic and mild activation during glycosidations that produce desired glycosides exclusively, scalable route to the synthesis of unnatural and expensive iduronic acid, minimal number of steps and facile purifications, shared use of functionalized building blocks and excellent process efficiency are the salient features.

Peritoneal Proteoglycans: Much more than Ground Substance

Recent advances in the field of glycobiology have exposed a multitude of biological processes that are controlled or influenced by proteoglycans, in both physiological and pathological conditions ranging from early embryonic development, inflammation, and fibrosis to tumor invasion and metastasis. The first part of this article reviews the biosynthesis of proteoglycans and their multifunctional roles in health and disease; the second part of this review focuses on their putative roles in peritoneal homeostasis and peritoneal inflammation and fibrosis in the context of chronic peritoneal dialysis and peritonitis.

Venous Thromboembolism in Special Populations: Preexisting Cardiopulmonary Disease, Cirrhosis, End-Stage Renal Disease, and Asplenia

Venous thromboembolism (VTE) is a common cause of morbidity and mortality. Presence of preexisting conditions, such as cardiopulmonary diseases, cirrhosis, renal dysfunction, and asplenia, commonly occurs in VTE patients. Moreover, these conditions often are risk factors for developing VTE. These preexisting conditions make VTE diagnosis and treatment challenging and worsen outcomes. Current guidelines do not include detailed features in the diagnosis and management of patients with preexisting conditions. This review discusses presence of VTE in patients with preexisting cardiopulmonary diseases, cirrhosis, renal dysfunction, and asplenia.

Chronic kidney disease and anticoagulation: from vitamin K antagonists and heparins to direct oral anticoagulant agents

Anticoagulation in patients with impaired kidney function can be challenging since drugs' pharmacokinetics and bioavailability are altered in this setting. Patients with chronic kidney disease (CKD) treated with conventional anticoagulant agents [vitamin K antagonist (VKA), low-molecular weight heparin (LMWH) or unfractionated heparin (UFH)] are at high risk of bleeding events (both non-major and major clinically relevant bleeding). While anticoagulation reduces the risk of thromboembolic events, the co-existing bleeding risk and the fact that the most commonly used anticoagulation agents are eliminated via the kidneys pose additional challenges. More recently, two classes of direct oral anticoagulant agents (DOACs) have been investigated for the prevention and management of venous thromboembolic events: the direct factor Xa inhibitors rivaroxaban, apixaban and edoxaban, and the direct thrombin inhibitor dabigatran. In this review, we discuss the complex challenges and the practical considerations associated with the management of anticoagulation treatment in patients with CKD, with a special focus on DOACs.

Effectiveness of heparin eye drops in paraquat-induced ocular injury

PURPOSE

To evaluate the efficacy of heparin eye drops in the treatment of paraquat-induced ocular surface injury.

DESIGN AND METHODS

In this retrospective study, we included 25 patients (31 eyes) with paraquat-induced ocular surface injury, who attended the Affiliated Hospital of Weifang Medical University between October 2008 and October 2013. The patients were split into two groups according to whether or not received heparin eye drops. The clinical data were compared between the two groups, i.e. clinical histories, results of examinations, treatments and outcomes.

RESULTS

Eleven patients (group A, 15 eyes) received prompt irrigation with 0.9% saline every two hours, 0.1% pranoprofen eye drops four times a day, 20% autologous serum every two hours, recombinant bovine basic fibroblast growth factor eye-gel two times a day, oral vitamin C 2.0 g and prednisone 30 mg daily. Fourteen patients (group B, 16 eyes) received additional treatment with heparin eye drops. Ten eyes in group A and seven eyes in group B developed a pseudomembrane on the ocular surface at significantly different rate (mean ± SD) of 1.20 ± 1.01 and 0.43 ± 0.51, respectively (t = 2.66, p = 0.01). Seven eyes among 10 had a pseudomembrane reoccurred in group A while none had a pseudomembrane reoccurred in group B (Fisher's exact test, p = 0.01). No significant differences were seen in the duration of epithelial recovery between the two groups: 15.13 ± 5.13 days in group A and 16.81 ± 5.56 days in group B (t = 0.87, p = 0.39). After the treatment, mild corneal opacity and pannus were observed in five patients of group A and four patients of group B, without any significant difference between the two groups (p = 0.70).

CONCLUSIONS

The paraquat-induced ocular surface injury observed in this case series was characterized by the formation of conjunctival pseudomembrane with good prognosis and mild complications. Heparin eye drops reduce the occurrence, especially the reoccurrence of pseudomembrane. Further studies are warranted.

The role of heparins and nano-heparins as therapeutic tool in breast cancer

Glycosaminoglycans are integral part of the dynamic extracellular matrix (ECM) network that control crucial biochemical and biomechanical signals required for tissue morphogenesis, differentiation, homeostasis and cancer development. Breast cancer cells communicate with stromal ones to modulate ECM mainly through release of soluble effectors during cancer progression. The intracellular cross-talk between cell surface receptors and estrogen receptors is important for the regulation of breast cancer cell properties and production of ECM molecules. In turn, reorganized ECM-cell surface interface modulates signaling cascades, which regulate almost all aspects of breast cell behavior. Heparan sulfate chains present on cell surface and matrix proteoglycans are involved in regulation of breast cancer functions since they are capable of binding numerous matrix molecules, growth factors and inflammatory mediators thus modulating their signaling. In addition to its anticoagulant activity, there is accumulating evidence highlighting various anticancer activities of heparin and nano-heparin derivatives in numerous types of cancer. Importantly, heparin derivatives significantly reduce breast cancer cell proliferation and metastasis in vitro and in vivo models as well as regulates the expression profile of major ECM macromolecules, providing strong evidence for therapeutic targeting. Nano-formulations of the glycosaminoglycan heparin are possibly novel tools for targeting tumor microenvironment. In this review, the role of heparan sulfate/heparin and its nano-formulations in breast cancer biology are presented and discussed in terms of future pharmacological targeting.

Sulfated polysaccharide heparin used as carrier to load hydrophobic lappaconitine

One-step self-assembly was used to prepare pH-sensitive lappaconitine-loaded low-molecular-weight heparin (LMWH-LA) and to demonstrate that the sulfur group promotes dissolution and has synergistic effect on the analgesic property of lappaconitine (LA). The LMWH-LA was characterized in terms of releasing behavior, pH-sensitivity, analgesic activity and anticoagulation property. The drug loading level of LA in low-molecular-weight heparin (LMWH) reached 24.3% (w/w). The LA, self-assembled in LMWH, released faster in an acidic environment than that in neutral or alkaline environments. Analgesic experiments showed that the LMWH-LA had earlier onset time and longer duration than the LA. Compared with LMWH, the LMWH-LA can reduce clotting time more effectively. These results suggest that the LMWH is a good template and has great potential to achieve synergistic effect of LA. In addition, similar macromolecular structure can be used as a new natural polymeric carrier for loading hydrophobic alkaloids.

A systematic review on the accumulation of prophylactic dosages of low-molecular-weight heparins (LMWHs) in patients with renal insufficiency

PURPOSE

Although therapeutic dosages of most low-molecular-weight heparins (LMWHs) are known to accumulate in patients with renal insufficiency, for the lower prophylactic dosages this has not been clearly proven. Nevertheless, dose reduction is often recommended. We conducted a systematic review to investigate whether prophylactic dosages of LMWH accumulate in renal insufficient patients.

METHODS

A comprehensive search was conducted on 17 February 2015 using Embase, Medline, Web of Science, Scopus, Cochrane, PubMed publisher, and Google scholar. The syntax emphasized for LMWHs, impaired renal function, and pharmacokinetics. The search yielded 674 publications. After exclusion by reading the titles, abstracts, and if necessary the full paper, 11 publications remained.

RESULTS

For dalteparin and tinzaparin, no accumulation was observed. Enoxaparin, on the other hand, did lead to accumulation in patients with renal insufficiency, although not in patients undergoing renal replacement therapy. Bemiparin and certoparin also did show accumulation. No data were available for nadroparin.

CONCLUSIONS

In this systematic review, we show that prophylactic dosages of tinzaparin and dalteparin are likely to be safe in patients with renal insufficiency and do not need dose reduction based on the absence of accumulation. However, prophylactic dosages of enoxaparin, bemiparin, and certoparin did show accumulation in patients with a creatinine clearance (CrCl) below 30 ml/min, and therefore, dose reduction is required. The differences in occurrence of accumulation seem to depend on the mean molecular weight of LMWHs.

Over-dialysis plasma RANTES increase depends on heparin dose and cardiovascular disease status

PURPOSE

The lifespan of maintenance hemodialysis patients is reduced mainly because of cardiovascular complications due to accelerated atherosclerosis and impaired angiogenesis. We aimed to compare the effect of unfractionated heparin (UFH) and enoxaparin used as anticoagulants during hemodialysis (HD) on circulating levels of heparin-binding, anti-angiogenic Endostatin, pro-inflammatory RANTES (Regulated upon Activation, Normal T cell Expressed and Secreted), and MCP-1 (Monocyte Chemoattractant Protein-1).

METHODS

We enrolled 22 chronic HD patients, who were randomly assigned to either enoxaparin (n=11) or UFH (n=11) anticoagulation, and followed prospectively for 12 weeks before crossing over to the alternate therapy for further 12 weeks. The factors were measured (ELISA) at the start, 10 and 180 min of HD, and compared to 20 healthy volunteers.

RESULTS

The baseline Endostatin, RANTES, and MCP-1 levels in patients were higher than in controls and comparable during enoxaparin and UFH treatment. RANTES significantly increased during both enoxaparin and UFH anticoagulated HD, while over-HD Endostatin and MCP-1 levels remained stable regardless of the heparin sort. About 25% RANTES increase after 10 min of HD positively correlated with the dose of both heparins and HD duration. The switch from enoxaparin to UFH treatment had no impact on the levels of parameters studied. Patients with ischemic heart disease had less RANTES increase after 180 min of HD especially during enoxaparin treatment.

CONCLUSION

RANTES is dose-depended and transitory increased in response to both UFH and enoxaparin administration during HD. Cardiovascular disease status occurred to be the most important predictor of its over-HD level.

Use and safety of unfractionated heparin for anticoagulation during maintenance hemodialysis

Anticoagulation is essential to hemodialysis, and unfractionated heparin (UFH) is the most commonly used anticoagulant in the United States. However, there is no universally accepted standard for its administration in long-term hemodialysis. Dosage schedules vary and include weight-based protocols and low-dose protocols for those at high risk of bleeding, as well as regional anticoagulation with heparin and heparin-coated dialyzers. Adjustments are based largely on clinical signs of under- and overanticoagulation. Risks of UFH use include bleeding, heparin-induced thrombocytopenia, hypertriglyceridemia, anaphylaxis, and possibly bone mineral disease, hyperkalemia, and catheter-associated sepsis. Alternative anticoagulants include low-molecular-weight heparin, direct thrombin inhibitors, heparinoids, and citrate. Anticoagulant-free hemodialysis and peritoneal dialysis also are potential substitutes. However, some of these alternative treatments are not as available as or are more costly than UFH, are dependent on country and health care system, and present dosing challenges. When properly monitored, UFH is a relatively safe and economical choice for anticoagulation in long-term hemodialysis for most patients.

Selective Granulocyte and Monocyte Apheresis as a Non-Pharmacological Option for Patients with Inflammatory Bowel Disease

Ulcerative colitis and Crohn's disease are the two most prevalent inflammatory bowel diseases. In both cases, the medically refractory and steroid-dependent type presents a therapeutic challenge. To help resolve this problem, a mainly Japanese team developed a new therapeutic option. There are two systems, both of which are able to selectively remove the main mediators of the disease, namely the activated pro-inflammatory cytokine-producing granulocytes and monocytes/macrophages, from the patient's blood circulation (GMA = granulocyte monocyte apheresis). One of the two systems is the Adacolumn( (®) ) (Immunoresearch Laboratories, Takasaki, Japan) consisting of the ADA-monitor and a single-use column, which contains approximately 35,000 cellulose acetate beads. The exact mode of action is not yet sufficiently understood, but however, a modulation of the immune system takes place. As a result, less pro-inflammatory cytokines are released. Furthermore, the production of anti-inflammatory interleukin-1 receptor antagonist is increased, and the apoptosis of granulocytes boosted. The decreased LECAM-1-expression on leukocytes impedes the leukotaxis to the inflamed tissue, and CD10-negative immature granulocytes appear in the peripheral blood. Another effect to be mentioned is the removal of the peripheral dendritic cells and the leachate of regulatory T cells (T-regs). The second system is the Cellsorba( (®) ) FX Filter (Asahi Medical, Tokyo, Japan). The range of efficiency, the indication, and the procedure are very similar to the Adacolumn. Solely the additional removal of lymphocytes can possibly limit the implementation since lymphopenia can increase the risk of autoimmune disease. Both systems provide a low-risk therapy with few adverse reactions. ASFA recommendations for GMA in inflammatory bowel disease are 2B due to the fact that not enough randomized double-blind studies are available to proof the efficacy of this treatment.

Tinzaparin versus dalteparin for periprocedure prophylaxis of thromboembolic events in hemodialysis patients: a randomized trial

BACKGROUND

Low-molecular-weight heparin (LMWH) is cleared predominantly by the kidneys and hence there is uncertainty about the safety of its use in hemodialysis (HD) patients. Our primary objective was to compare whether tinzaparin and dalteparin differentially accumulate in HD patients.

STUDY DESIGN

Open-label randomized controlled trial.

SETTING & PARTICIPANTS

HD patients undergoing periprocedure bridging anticoagulation.

INTERVENTION

After warfarin therapy was discontinued, participants were randomly assigned to either 3 daily doses of tinzaparin (175 IU/kg) or dalteparin (200 IU/kg), with 2 intervening HD treatments between the first dose of study drug and their procedure.

OUTCOMES

The primary outcome was predialysis anti-Xa levels 20 to 24 hours after the third LMWH dose (therapeutic target, <0.2 IU/mL). Secondary outcomes included thromboembolic events and major bleeding.

RESULTS

Of 29 eligible and consenting patients, 17 patients received tinzaparin and 12 patients received dalteparin. Mean predialysis anti-Xa level 20-24 hours after the third LMWH dose was 0.37 ± 0.23 (SD) IU/mL for tinzaparin and 0.62 ± 0.41 IU/mL for dalteparin (P = 0.1), indicating clinically important accumulation for both drugs. No invasive procedures were canceled due to study drug accumulation. 4 patients experienced serious adverse events (1 major bleed after traumatic arteriovenous fistula puncture in the tinzaparin arm, 2 non-ST-elevation myocardial infarctions [1 in each group], and 1 upper-extremity deep venous thrombosis [dalteparin group]).

LIMITATIONS

Small sample size.

CONCLUSIONS

Dalteparin and tinzaparin significantly accumulate in HD patients at therapeutic doses. "Bridging therapy" with LMWHs at therapeutic doses in HD patients who require temporary interruption of warfarin therapy has the potential for complications and is of uncertain benefit. Other anticoagulation strategies, including no bridging therapy or intravenous heparin, need comparative evaluation in this unique patient population.

Enoxaparin versus unfractioned heparin as anticoagulant for continuous venovenous hemodialysis: a randomized open-label trial

AIM

In this study we aimed to compare the efficacy and safety of enoxaparin with unfractioned heparin (UFH) as anticoagulant for continuous venovenous hemodialysis (CVVHD).

METHODS

An open-label randomized controlled trial was carried out in an intensive care unit (ICU) where 40 patients with acute renal failure (ARF) who needed continuous renal replacement therapy were randomized to receive UFH (n=21) or enoxaparin (n=19). Coagulation parameters were evaluated, and antithrombotic activity of UFH was measured by activated partial thromboplastin time (aPTT) and for enoxaparin by anti-factor Xa activity. Primary outcomes were thrombosis of the extracorporeal circuit and bleeding, classified as major or minor.

RESULTS

Minor bleeding episodes were observed only in patients anticoagulated with enoxaparin (26 vs. 0%, p=0.018). Comparing patients with or without bleeding after 24 hours of therapy, the level of anticoagulation tended to be higher (anti-factor Xa: 1.62 vs. 1.13 IU/mL, p=0.09) and the platelet count to be lower [107+/-53 vs. 229+/-84 (x10(3)/microL), p=0.09] in patients who bled, but without statistical difference. Filter life span of enoxaparin and UFH groups was similar (43+/-15 vs. 52+/-18 hr, p=0.10), as well as the proportion of circuit clotting.

CONCLUSION

Weight-unadjusted enoxaparin in patients with ARF in CVVHD was associated with an increased rate of bleeding, a finding that addresses the need to adjust drug dose and to monitor anti-factor Xa activity during dialysis. No benefit to prolong dialysis circuit survival was found with enoxaparin. In patients who do not present contraindication for systemic anticoagulation, UFH remains an effective and low-cost option.

HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: The Safety of Heparins in End-Stage Renal Disease

In patients on chronic dialysis, unfractionated heparin (UFH) is the most commonly used agent for anticoagulation of the hemodialysis extracorporeal circuit, for hemodialysis catheter "locking" between dialysis treatments, and for nondialysis indications such as venous thromboembolic disease, peripheral vascular disease, and acute coronary artery disease. Potentially serious complications of UFH, such as hemorrhage, osteoporosis, and thrombocytopenia, have led to consideration of other options for anticoagulation, including low molecular weight heparin (LMWH) and direct thrombin inhibitors (DTIs). LMWH can be used for anticoagulation of the hemodialysis circuit, but whether this has significant benefit compared to UFH remains to be proven. Because of the somewhat unpredictable risk of severe bleeding complications when LMWH is used for other indications in dialysis patients, UFH rather than LMWH is preferred for treatment of thromboembolic disease in these patients. DTIs have been used for anticoagulation in dialysis patients with heparin-induced thrombocytopenia (HIT), with argatroban being the preferred agent if heparin-free hemodialysis cannot be performed. UFH still remains the preferred anticoagulant in the vast majority of dialysis patients requiring systemic anticoagulation and for anticoagulation of the extracorporeal hemodialysis circuit.

HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: Anticoagulation and Continuous Renal Replacement Therapy

More than half of patients with acute renal failure in the intensive care unit require dialysis, and the majority of them have significant hemodynamic instability. Continuous renal replacement therapy (CRRT) is often the preferred dialysis modality in these patients. One requirement for CRRT is anticoagulation, which can expose patients to the risk of bleeding. However, absence of effective anticoagulation may result in clotting of the CRRT circuit and subsequently less effective treatment. While heparins are widely used for anticoagulation, because of potential side effects such as bleeding and heparin-induced thrombocytopenia, alternative anticoagulation protocols should be considered. Citrate anticoagulation, regional heparin/protamine, predilution, r-hirudin, prostacyclin, and nafamostat are among these methods.